[mlir] Consider mlir-linalg-ods-gen as a tablegen tool in build (#75093)

There is a bit of an issue with how `mlir-linalg-ods-yaml-gen` is
classified in the MLIR build. Due to it being a tool, it is excluded
from the install when using `-DLLVM_BUILD_TOOLS=OFF`. However, it is a
necessary component of the build, so it can cause build issues with
users of the installed LLVM, and so I think it should not be excluded.

It is a tablegen-like tool, so my solution is to reclassify it that way
in the build.